I have it on top of my Element using a 20 foot NRS strap cross weaved on my factory roll cage. My playboat is out of the way on it's side against the stackers.
Anyway...the sit on top seems really secure but just to make sure I attached a 15 foot NRS strap to the bow and made a bow line to the tow hook just right of the center of the Honda (when facing the vehicle). I would still like easy access to the trunk of the car (traveling with a one year old) so I didn't attach a stern line....and my biggest worry was the stern of the boat slipping to the left away from the stackers (which it is pushed against).
It seems like the bow line being a little offset will provide additional protection of forcing the stern to the center of the Honda and firmly against the stackers.
Does this sound good to go? Potential problems? Problems with just having a bow line?
Like I said...it all seems really secure but I've never transported such a long boat such a long distance and I just want to be sure it's not going anywhere.